Paper sizing



Patented Nov. 22, 1938 7 UNITED; STATES rPATENT oF'F-l CE No Drawing; -Application March 12,1936, Serial N0. 68,449

2 Claims. (01'. 1341-7-2 Thisinvention relates to the making of sizing material such as for paper, and more particularly to a size having rosin as its chief component and in making of which, ammonia is the alkali used for 'saponification. That is the invention revolves about ammonium resinate as asizing material.

In the manufacture of rosin soap for paper sizing, the common practice is to boil the rosin in an aqueous solution'of sodium carbonate or caustic soda using an amount of water in the boiling process, which'is less than the amount of rosin used. The commercial rosin size sold to paper mills, contains from 30% to of water. These sizes are manufactured by boiling the rosin at temperatures between 180 F. and 212 F. The paper manufacturer dilutes such a sizing material with water by the use of emulsifying systems for producing sizing solutions containing from 2% to 4% of rosin.

Another known method of making rosin solutions consists essentially in circulating a cold solution of caustic soda in a container filled' with coarsely crushed rosin in a manner described for instance in U. S. Patent No. 1,759,526. This method is used to make a dilute sizing solution of sodium resinate but this and all other known methods are unsuitable for making a dilute sizing solution of ammonium resinate. So one of the objects of this invention is devising a method whereby such a solution offammonium resinate can be made satisfactorily.

The methods heretofore used in making size which involve boiling in open tanks, cannot be used in connection with ammonium resinate because the ammonia starting material is a gas in aqueous solution and therefore cannot be boiled with rosin without losing the alkali by volatilization. In attempting to make ammonium resinate sizing solution, other difliculties are encountered, because that material is of such a viscous character that it is difficult to make a, rosin soap in concentration of over 6% of rosin for the reason that it sets to a jell and cannot be stirred sufficiently to complete the reactions of saponification. A true ammonium resinate has a viscosity like syrup when cold even if it contains no more than 3% of rosin. Therefore, when it is attempted to obtain a reaction between ammonia solution and lumps of rosin a solid ammonium resinate forms upon the unsaponified rosinlumps to such an extent that a protective coating is formed thereon which prevents further saponification thereof. So another object of this invention is to devise a process for making such a size while avoiding these difliculties.

To this end, I pulverize'the rosin so that it will preferably pass thru a 40-mesh screen and when I- bring about the saponificationof the rosin with "ammonia "as a starting material, under certain critical conditions of temperature and of concentration, I am able to bring about arapid and uniform formation" of ammonium resinate. I

have found that there exists definite limits for both of these phases which must be carefully 'observedto obtain a satisfactory method of producing this material. The optimum concentration is substantially 3% for the rosin and at that concentration the optimum temperature is substantially 100 F. It is possible to use a temperature lying between 60 F. and 140 F. Also it is possible to saponify the rosin to a 10% concentration by raising the temperature of the reaction mass. to 130 F., thus allowing only a small factor of safety below that temperature at which the rosin will agglomerate. It is difficult to carry out a commercial operation at a concentration about 6% of rosin.

Onthe other hand, it is possibleto saponify the rosin at 1% concentration by using the higher safe limit of temperature of the'mass, but under such circumstances, the ammonia concentration must'be increased above an economical limit. The commercial limits of the concentration of the rosinare from 1% to 6% but 3% is the ideal concentration to make use of. The temperature that is best to use may vary slightly with the particular kind of rosin used for some kinds will acquire sticky properties at lower temperatures than others. Accordingly, it is desirable to use a temperature safely below that at which the rosin being used becomes sticky, but whatever this is, it will be found to be a high enough temperature to cause saponification of the rosin by virtue of the use of a reasonable amount of ammonia. The proportion of rosin to ammonia must be such that there is avoided incomplete saponification of the rosin. Further the rosin used should be in a finely ground or pulverized condition to assure maximum dispersion thereof in the ammonia solution, in order to get prompt and complete reaction between the rosin particles and the ammonia.

One method of carrying out this invention is as follows: 3 parts of pulverized rosin is mixed with 100 parts of water, containing a sufficient quantity of ammonia to saponify the rosin. While the mixture is stirred it is heated to a temperature of approximately 100 F. Under these conditions, saponification takes place rapidly and y no ammonia is lost due to volatilization. As the temperature varies substantially from this ideal, the results are less satisfactory. For instance at a temperature of F., the rate of saponification is very slow, and a large excess of ammonia would have to be used. If the temperature should be raised to 140 F. before all of the rosin particles are saponified, or if powdered rosin should be added to an ammonia solution at this temperature, the rosin particles would become sticky and form into a lumpy mass, which would practically prevent saponification or at least satisfactorily complete saponification.

A feasible commercial arrangement for carrying out this invention would be an open tank equipped with agitators. In a tank containing 10,000 pounds of water, should be added about 120 pounds of 26 B. aqueous ammonia together with 300 pounds of powdered rosin. The water can be heated either before or after adding the ingredients. The temperature to which the water should be heated normally is approximately F. On stirring the mixture saponification takes place rapidly and within 10 or 30- minutes all of the rosin will be found to have been dissolved and converted into ammonium resinate. This is the sizing material of this invention and is ready for use. It will remain fluid for a considerable length of time.

Altho an excess of ammonia is used over that theoretically required for saponification, this excess ammonia does not do any harm to the size in the same way that an excess of soda would. And as the size is allowed to stand the excess ammonia can be allowed to evaporate while stirring either with or without heat until the size turns from a solution into an emulsion, without destroying the sizing properties of this product.

On the other hand, a size containing an excess of ammonia is more stable when used for sizing in the presence of hard water. It is therefore, possible by the process of making this size to adjust it to the conditions under which it is to be used, by varying the amount of ammonia. After the size is made at a concentration of approximately 3% it may be further diluted if it is desirable to have it in a very fluid state after it has become cold.

I claim:

1. The method of making directly a dilute solution of ammonium resinate which comprises mixing together 3 parts of pulverized rosin, 100 parts JUDSON A. DE CEW. 

